You first need to jailbreak your iPhone 3G, 3GS or iPhone 4 before unlocking it. Get jailbreak guide here. In this tutorial you will learn how to unlock 3G, 3GS or iPhone 4 firmware 4.0.1 so you can use other SIM cards to run on your iPhone

Importan First thing you need to do is to go to Cydia on your iPhone. Once it is open, go to Manage and then to Sources and then click Edit and then Add at the top. Type repo666.ultrasn0w.com and click Add Source and then you gotta go to .